An athlete drinks measured amounts of fluid before, during, and after training to replace sweat losses. That practice is hydration. Maintaining fluid balance supports performance and reduces heat-related risk.

Dehydration impairs endurance, strength, and cognitive function. Sweat rates vary with intensity, climate, and individual physiology, so fixed rules give way to personal monitoring. Body-mass changes across sessions offer a practical estimate of fluid loss. Electrolyte replacement becomes important when sweating is heavy and prolonged.

Sports drinks can help when sessions last longer than an hour or when high intensity produces large salt losses. Over-drinking carries its own risks. Practical habits—starting sessions well hydrated, drinking to thirst with awareness, and rehydrating afterward—cover most needs. Coaches who schedule fluid breaks and provide access to drinks protect both performance and health.

• Maintaining adequate body fluid levels
• Supports performance and temperature regulation
• Guided by sweat loss and individual needs
• Includes pre-, during-, and post-exercise intake